1. Field of the Invention
The present invention relates to a numerical control apparatus which controls a machine tool having two linear moving axes orthogonal to each other and a pivot axis.
2. Description of the Related Art
As a machine tool for machining a three-dimensional-shaped workpiece, a machine having an actuator for linearly operating at least three orthogonal axes is used. In this case, a drive system such as a guide and a ball screw applied to moving ranges of the axes are required. Even though the drive system is required to be reduced in size, the drive system cannot be easily reduced in size. A machine tool which includes a simple configuration, in place of the three orthogonal linear moving axes, to make it possible to achieve a reduction in size and to perform machining of an arbitrary three-dimensional shape equivalent to machining performed by three orthogonal linear moving axes is not known.
In order to reduce the size of the above machine tool or to simplify the drive system, an easy and simple drive system is necessary in place of the linear axes. If an actuator which does not use linear moving axes is used, formation of a program for a numerical control apparatus in which commands for workpiece machining are formed in three orthogonal moving directions in workpiece machining for a three-dimensional shape must be changed, usability is also deteriorated, and inconvenience increases.